Add validator.

2 files changed, 43 insertions, 2 deletions

diff --git a/Timeline/Services/UserAvatarService.cs b/Timeline/Services/UserAvatarService.cs
index 4f11978c..2a73cde5 100644
--- a/Timeline/Services/UserAvatarService.cs
+++ b/Timeline/Services/UserAvatarService.cs
@@ -2,6 +2,8 @@
 using Microsoft.EntityFrameworkCore;

 using Microsoft.Extensions.DependencyInjection;

 using Microsoft.Extensions.Logging;

+using SixLabors.ImageSharp;

+using SixLabors.ImageSharp.Formats;

 using System;

 using System.IO;

 using System.Linq;

@@ -45,6 +47,11 @@ namespace Timeline.Services
         Task<Avatar> GetDefaultAvatar();

     }

 

+    public interface IUserAvatarValidator

+    {

+        Task<(bool valid, string message)> Validate(Avatar avatar);

+    }

+

     public interface IUserAvatarService

     {

         /// <summary>

@@ -87,6 +94,31 @@ namespace Timeline.Services
         }

     }

 

+    public class UserAvatarValidator : IUserAvatarValidator

+    {

+        public Task<(bool valid, string message)> Validate(Avatar avatar)

+        {

+            return Task.Run(() =>

+            {

+                try

+                {

+                    using (var image = Image.Load(avatar.Data, out IImageFormat format))

+                    {

+                        if (!format.MimeTypes.Contains(avatar.Type))

+                            return (false, "Image's actual mime type is not the specified one.");

+                        if (image.Width != image.Height)

+                            return (false, "Image is not a square, aka width is not equal to height.");

+                    }

+                    return (true, "A good avatar.");

+                }

+                catch (UnknownImageFormatException e)

+                {

+                    return (false, $"Failed to decode image. Exception: {e} .");

+                }

+            });

+        }

+    }

+

     public class UserAvatarService : IUserAvatarService

     {

 

@@ -95,12 +127,14 @@ namespace Timeline.Services
         private readonly DatabaseContext _database;

 

         private readonly IDefaultUserAvatarProvider _defaultUserAvatarProvider;

+        private readonly IUserAvatarValidator _avatarValidator;

 

-        public UserAvatarService(ILogger<UserAvatarService> logger, DatabaseContext database, IDefaultUserAvatarProvider defaultUserAvatarProvider)

+        public UserAvatarService(ILogger<UserAvatarService> logger, DatabaseContext database, IDefaultUserAvatarProvider defaultUserAvatarProvider, IUserAvatarValidator avatarValidator)

         {

             _logger = logger;

             _database = database;

             _defaultUserAvatarProvider = defaultUserAvatarProvider;

+            _avatarValidator = avatarValidator;

         }

 

         public async Task<Avatar> GetAvatar(string username)

@@ -157,11 +191,15 @@ namespace Timeline.Services
                 {

                     _database.UserAvatars.Remove(avatarEntity);

                     await _database.SaveChangesAsync();

+                    _logger.LogInformation("Removed an entry in user_avatars.");

                 }

             }

             else

             {

-                // TODO: Use image library to check the format to prohibit bad data.

+                (bool valid, string message) = await _avatarValidator.Validate(avatar);

+                if (!valid)

+                    throw new AvatarDataException(avatar, $"Failed to validate image. {message}");

+

                 if (avatarEntity == null)

                 {

                     user.Avatar = new UserAvatar

@@ -176,6 +214,7 @@ namespace Timeline.Services
                     avatarEntity.Data = avatar.Data;

                 }

                 await _database.SaveChangesAsync();

+                _logger.LogInformation("Added or modified an entry in user_avatars.");

             }

         }

     }

@@ -186,6 +225,7 @@ namespace Timeline.Services
         {

             services.AddScoped<IUserAvatarService, UserAvatarService>();

             services.AddSingleton<IDefaultUserAvatarProvider, DefaultUserAvatarProvider>();

+            services.AddSingleton<IUserAvatarValidator, UserAvatarValidator>();

         }

     }

 }

diff --git a/Timeline/Timeline.csproj b/Timeline/Timeline.csproj
index 29ff3354..3855e0d1 100644
--- a/Timeline/Timeline.csproj
+++ b/Timeline/Timeline.csproj
@@ -12,5 +12,6 @@
         <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.2.3" />

         <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.2.0" />

         <PackageReference Include="Pomelo.EntityFrameworkCore.MySql.Design" Version="1.1.2" />

+        <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0-dev002868" />

     </ItemGroup>

 </Project>